Subject:
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Resistances of touch sensors and lamps
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 8 Oct 2000 15:05:07 GMT
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Viewed:
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429 times
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Hi all,
I played around with touch sensors and a lamp this weekend,
trying to measure their resistance. Since my Ohmmeter
proved rather unreliable, the values keep wandering around
and it seemed zero was not well adjusted, I just took a look
at the raw values on the RCX instead. These were the findings:
- The value for my lamp was 4, which is very low and makes
it impractical to use it in parallel (so forget the circuit
in my previous posting).
- The touch sensors showed quite some variation in their
resistance when pressed, to the point that I can
apparently, from the values they show, distinguish three
of them in parallel on a single input (No's 3, 2 and 4):
No 1: 58
No 2: 66
No 3: 150
No 4: 45
No 5: 48
Red: 28
Yellow: 27
White: 50
However, the margin was quite slim and I haven't tried
this with a program yet, and I'm a bit in doubt whether
it will be stable over time.
- The variation is greater than that obtained by adding a
lamp in series, but a lamp may help to nudge around the
values just a bit to make it work.
- The resistance of cable is very low, 8m made of 30 cables
gave me a value between 1 and 2. So cable is not a practical
resistor, short of going into the hundreds of meters.
Keep on constructing
Jürgen
--
Jürgen Stuber <stuber@loria.fr>
http://www.loria.fr/~stuber/
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Message has 1 Reply:
 | | Re: Resistances of touch sensors and lamps
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| I have been keeping an eye on this thread and feel compelled to add my observation and experience; The touch sensors tend to exhibit quite an extended range of resisitance values as they are depressed. I have a couple which start as high as 7k on (...) (24 years ago, 9-Oct-00, to lugnet.robotics)
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